Decreased Radiation Exposure and Increased Efficacy in Extracorporeal Lithotripsy Using a New Ultrasound Stone Locking System

Abstract

Purpose:

To compare fluoroscopy duration, radiation dose, and efficacy of two ultrasound stone localization systems during extracorporeal shockwave lithotripsy (SWL) treatment.

Patients and Methods:

Monocentric prospective data were obtained from patients consecutively treated for renal stones using the Sonolith^® i-sys (EDAP TMS) lithotripter, with fluoroscopy combined with ultrasound localization using an “outline” Automatic Ultrasound Positioning Support (AUPS) (group A), or the “free-line” Visio-Track (VT) (EDAP-TMS) hand-held three-dimensional ultrasound stone locking system (group B). Efficacy rate was defined as the within-groups proportion stone free or with partial stone fragmentation not needing additional procedures. Statistical analysis used Pearson chi-square tests for categoric variables, nonparametric Mann-Whitney tests for continuous variables, and linear regression for operator learning curve with VT. Continuous variables were reported as median (range) values.

Results:

Patients in group A (n=73) and group B (n=81) were comparable in baseline characteristics (age, kidney stone size, others) and in SWL application (duration, number of shocks, energy [Joules]). During SWL, the median (range) duration (seconds) of radiation exposure was 159.5 (0–690) in group A and 3.5 (0–478) in group B (P<0.001) and irradiation dose (mGy.cm²), 10598 (0–54843) in group A and 163 (0–13926) in group B (P<0.001). Fluoroscopy time significantly decreased with operator experience using VT. The efficacy rate was 54.5% in group A and 79.5% in group B (P=0.001).

Conclusion:

VT significantly reduced fluoroscopy use during SWL and the duration and dose of patient exposure to ionizing radiation. Stone treatment efficacy was significantly greater with VT mainly because of a better real-time monitoring of the stone.